首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   169篇
  免费   11篇
  2022年   1篇
  2018年   1篇
  2017年   1篇
  2016年   4篇
  2015年   2篇
  2014年   6篇
  2013年   12篇
  2012年   6篇
  2011年   7篇
  2010年   3篇
  2009年   6篇
  2008年   10篇
  2007年   10篇
  2006年   11篇
  2005年   11篇
  2004年   15篇
  2003年   20篇
  2002年   9篇
  2001年   1篇
  2000年   3篇
  1998年   2篇
  1997年   1篇
  1995年   3篇
  1994年   3篇
  1993年   3篇
  1992年   2篇
  1991年   1篇
  1990年   2篇
  1989年   1篇
  1987年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1974年   2篇
  1973年   2篇
  1972年   3篇
  1971年   2篇
  1970年   2篇
  1969年   2篇
排序方式: 共有180条查询结果,搜索用时 31 毫秒
171.
In order to examine the relationship between tobacco aroma and the nitrogen-containing compounds in the tobacco headspace volatiles, the volatiles of flue-cured, Burley and Turkish tobaccos collected with Tenax GC were analyzed by a gas chromatograph equipped with a flame thermionic detector. Of the 21 compounds identified in the chromatogram, 2,5-dimethylpyridine, 2,4-dimethylpyridine, pyrrole and N-methylpyrrole have not been previously reported as present in the tobacco headspace volatiles. By principal component analysis and stepwise discriminant analysis, three principal components and discriminant functions with four peaks were obtained. The results of these statistical analyses classified the samples into each variety respectively.  相似文献   
172.
IL-17 is a cytokine that induces neutrophil-mediated inflammation, but its role in protective immunity against intracellular bacterial infection remains unclear. In the present study, we demonstrate that IL-17 is an important cytokine not only in the early neutrophil-mediated inflammatory response, but also in T cell-mediated IFN-gamma production and granuloma formation in response to pulmonary infection by Mycobacterium bovis bacille Calmette-Guérin (BCG). IL-17 expression in the BCG-infected lung was detected from the first day after infection and the expression depended on IL-23. Our observations indicated that gammadelta T cells are a primary source of IL-17. Lung-infiltrating T cells of IL-17-deficient mice produced less IFN-gamma in comparison to those from wild-type mice 4 wk after BCG infection. Impaired granuloma formation was also observed in the infected lungs of IL-17-deficient mice, which is consistent with the decreased delayed-type hypersensitivity response of the infected mice against mycobacterial Ag. These data suggest that IL-17 is an important cytokine in the induction of optimal Th1 response and protective immunity against mycobacterial infection.  相似文献   
173.
Carbapenem‐resistant Acinetobacter baumannii has rapidly spread worldwide. This study investigated antibiotic susceptibility and genotypic resistance of 123 consecutive blood culture isolates of Acinetobacter species collected between 2003 and 2011 in two Japanese hospitals. The isolates were assigned to 13 species. Carbapenem resistance was detected in four isolates. Only one A. baumannii isolate had blaOXA‐23 together with ISAba1; the remaining three isolates had IMP‐1 metallo‐β‐lactamase. Quinolone resistance was detected in five isolates that had point mutations in the quinolone resistance‐determining region. The predominance of various non‐A. baumannii species and low prevalence of carbapenem resistance among blood culture isolates of Acinetobacter species in two Japanese hospitals were confirmed.  相似文献   
174.
Abl interactor (Abi) was identified as an Abl tyrosine kinase-binding protein and subsequently shown to be a component of the macromolecular Abi/WAVE complex, which is a key regulator of Rac-dependent actin polymerization. Previous studies showed that Abi-1 promotes c-Abl-mediated phosphorylation of Mammalian Enabled (Mena) and WAVE2. In addition to Abi-1, mammals possess Abi-2 and NESH (Abi-3). In this study, we compared the three Abi proteins in terms of the promotion of c-Abl-mediated phosphorylation and the formation of Abi/WAVE complex. Although Abi-2, like Abi-1, promoted the c-Abl-mediated phosphorylation of Mena and WAVE2, NESH (Abi-3) had no such effect. This difference was likely due to their binding abilities as to c-Abl. Immunoprecipitation revealed that NESH (Abi-3) is present in the Abi/WAVE complex. Our results suggest that NESH (Abi-3), like Abi-1 and Abi-2, is a component of the Abi/WAVE complex, but likely plays a different role in the regulation of c-Abl.  相似文献   
175.
The novel compound methyl-1-(3,4-dimethoxyphenyl)-3-(3-ethylvaleryl)-4-hydroxy-6,7,8-trimethoxy-2-naphthoate (S-8921) has hypocholesterolemic activity in animals and is expected to exhibit a similar activity in human. Reversed-phase high-performance liquid chromatography (HPLC) separation followed by radioimmunoassay (RIA) for human plasma samples (HPLC–RIA) and immunoaffinity extraction (IAE) followed by RIA for human urine samples (IAE–RIA) were developed for investigation of S-8921 behavior in clinical studies. For the RIA, antisera from rabbit and a radioiodine-labelled S-8921 were prepared by immunizing a conjugate of S-8921 with bovine serum albumin and by the Bolton and Hunter method, respectively. HPLC–RIA using a semi-micro column was very sensitive, that is a 0.05 ng/ml limit of quantitation in human plasma, and specific for unchanged form of S-8921. IAE–RIA using a centrifugal filtration tube completely eliminated the matrix effect of human urine, and was very feasible. The limit of quantitation was 0.10 ng/ml. RIA detection following HPLC or IAE proved to be very useful for the pharmaceutical analysis of extremely low drug concentrations in body fluids.  相似文献   
176.
The bacteriology of fresh and boiled squid sauce containing muscle has been studied. Bacterial numbers greatly increased only in the latter. Streptococcus spp. isolated from the fresh sauce showed anti-microbial activities to nine authentic strains tested, but not to Bacillus spp. which predominate in the fermented sauce.  相似文献   
177.
The ectopic distribution of synaptic ribbons in dendrites of mouse retinal bipolar cells was examined by using genetic ablation of metabotropic glutamate receptor subtype 6 (mGluR6), electron microscopy, and immunocytochemistry. Ectopic ribbons were observed in dendrites of rod and ON-cone bipolar cells in the mGluR6-deficient mouse but not in those of wild-type mice. The number of rod spherules facing the ectopic ribbons in mGluR6-deficient rod bipolar dendrites increased gradually during early growth and reached a plateau level of about 20% at 12 weeks. These ectopic ribbons were immunopositive for RIBEYE, a ribbon-specific protein, but the associated vesicles were immunonegative for synaptophysin, a synaptic-vesicle-specific protein. The presence of ectopic ribbons was correlated with an increase in the roundness of the invaginating dendrites of the rod bipolar cells. We further confirmed ectopic ribbons in dendrites of OFF-cone bipolar cells in wild-type retinas. Of the four types of OFF-cone bipolar cells (T1–T4), only the T2-type, which had a greater number of synaptic ribbons at the axon terminal and a thicker axon cylinder than the other types, had ectopic ribbons. Light-adapted experiments revealed that, in wild-type mice under enhanced-light adaptation (considered similar to the mGluR6-deficient state), the roundness in the invaginating dendrites and axon terminals of rod bipolar cells increased, but no ectopic ribbons were detected. Based on these findings and known mechanisms for neurotransmitter release and protein trafficking, the possible mechanisms underlying the ectopic ribbons are discussed on the basis of intracellular transport for the replenishment of synaptic proteins.  相似文献   
178.
Acetylated ferricytochrome c was employed for the detection of superoxide radicals (O2?) generated both in intact cells and in subcellular fractions of leukocytes. Certain saturated fatty acids, myristate in particular, induced the production of O2? in leukocytes, suggesting a correlation between the formation of O2? and the hydrophobic interaction of fatty acids with the leukocyte plasma membrane. As compared with O2? radical generation from phagocytizing leukocytes, a greater stimulation of O2? formation was observed in cells in which myristate was added. The enhanced activity which generated O2? in the cell-free system was located in a particulate fraction but not in the cytosol. The rate of O2? generation in the particulate fraction was higher in the presence of NADPH than in the presence of NADH. The effects of reagents such as KCN, 2,4-dichlorophenol and aminotriazole on the O2? generation in this fraction are examined and the nature of the O2? generating system is discussed.  相似文献   
179.
180.
Normal Faecal antigen-2 (NFA-2) and non-specific crossreactingantigen-2 (NCA-2), cross-reacting with anticarcinoembryonicantigen (CEA) antibodies, were found in normal human faececand meconium, respectively. Because NFA-2, NCA-2 and CEA areconsidered as the same gene products, NFA-2 and NCA-2 shouldbe normal counterparts of CEA produced by colon epithelial cellsof normal adults and fetuses, respectively. Comparison of sugarchain structures of these three antigens is indispensable inorder to unravel the stnaural alteration induced by malignanttransformation and development of colon epithelial cells. Thesugar chain structures of CEA (Yamashita,K. et al., Cancer Res.,47,3451–3459,1987) and NCA-2 (Yarnashita,K. et al., J.Bid Chem, 264,17873-17881,1989) were previously reported. Inthis paper, the structures of the oligosaccharides releasedfrom four NFA-2 samples by hydrazinolysis were studied by meansof lectin-affinity column chromatography, endo- and em-glycosidasedigestion, methylation analysis, hydrazinolys-nitrous acid deaminationand electrospray ionization mass spectrometry. NFA-2 contains24–27 mol of N-linked sugar chains/molecule, which issimilar to NCA-2 (27 mol) and CEA (24–27 mol). In contrastto CEA, which contains {small tilde} 8% high-mannose-type sugarchains all sugar chains of NFA-2 are mono- to tetra-antennarycomplex-type chains having four types of tri-mannosyl cores,with or without bisecting N-acetylglucosamine and fucose residues.The structures of their outer chain moieties comprise Galß1  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号